1. Field of the Invention
The present invention relates to an internal combustion engine, and more particularly, to a remote control system of an internal combustion engine.
2. Description of the Related Art
When an abnormality occurs in an internal combustion engine in a propulsion unit on a boat equipped with a plurality of propulsion units, the engine can be configured such that an engine speed of the engine (i.e., engine speed) is reduced in response to the abnormality to prevent overheating of the engine. If an engine in a propulsion unit in a normal condition is operated in the same state, the engine speed the normal engine and the abnormal engine can become unbalanced and operation stability can deteriorate.
When an attempt is made to reduce the engine speed of the abnormal internal combustion engine, there can be a case where a propeller of the internal combustion engine is forcefully rotated by a water flow, so that the engine speed is not reduced to a target low speed.
In Patent Document JP-B-Hei 6-33074, a control system that reduces both of the engine speed an internal combustion engine having caused an abnormality and the engine speed of a normally operating other internal combustion engine is proposed. In this system, an abnormality detector, when an abnormality occurs in an internal combustion engine in any propulsion unit of two propulsion units, detects an abnormality to reduce the engine speed of an internal combustion engine by operating an abnormality warning device installed to an internal combustion engine having caused the abnormality, while an abnormality warning detector installed to a normally operating internal combustion engine is operated to reduce the engine speed of a normally operating internal combustion engine, preventing a forceful rotation.
As illustrated in FIG. 4, a conventional control system of an internal combustion engine can have a right side control system 50R to give a warning against an abnormality of an internal combustion engine in a right side propulsion unit and a left side control system 50L to give a warning against an abnormality of an internal combustion engine in a left side propulsion unit. So-called mechanical type remote operation system has a propulsion unit and a remote control device connected by a connector such as a cable, and the control systems 50R, 50L include the abnormality detector 51R, 51L, the controller 52R, 52L, the abnormality warner 53R, 53L, and the warning canceller 54R, 54L.
The abnormality detector 51R, 51L include the overheating detection circuits 55R, 55L to detect overheating of an internal combustion engine and the oil reduction detection circuits 56R, 56L to detect oil reduction.
In addition, the abnormality warner 53R, 53L include buzzers 57R, 57L to give a warning when oil reduction or overheating is detected, the lamps 58R, 58L to give a warning when oil reduction is detected, and the engine speed reduction circuits 59R, 59L to give a warning by reducing an engine speed of an internal combustion engine when oil reduction or overheating is detected by these detection circuits.
Moreover, the controller 52R, 52L have the warning signal output circuits 60R, 60L to output a warning signal to give a warning to a an internal combustion engine side of the other propulsion unit based on an abnormality detecting signal from the overheating detection circuits 55R, 55L or the oil reduction detection circuits 56R, 56L. A warning signal output by these warning signal output circuits 60R, 60L is entered into the warning signal input circuits 61R, 61L on the other internal combustion engine side, and the state is retained in the retaining circuits 62R, 62L. This simultaneously operates the engine speed reduction circuits 59R, 59L of an internal combustion engine in a normal propulsion unit, reducing an engine speed of an internal combustion engine and operating the buzzers 57R, 57L to warn an operator.
For example, when an internal combustion engine in the right side propulsion unit is overheated or the amount of oil becomes smaller than a standard amount, the overheating detection circuits 55R detects overheating or the oil reduction detection circuits 56R detects oil reduction, and the buzzer 57R and the lamp 58R operate to inform an operator of the abnormality. If the overheating detection circuit 55R or the oil reduction detection circuits 56R operates, the operation signal is transmitted to the engine speed circuit 59R of the internal combustion engine in an abnormal right side compulsion system and the engine speed reduction circuit 59L of the internal combustion engine in a normal left side compulsion system. The signal transmitted from the engine speed reduction circuits 59R, 59L makes spark plugs of the internal combustion engine in the abnormal right side propulsion unit and an internal combustion engine in a normal left side propulsion unit fail, reducing an engine speed of each internal combustion engine.
In some cases where a mechanical type remote operation system is used, each electronic control device connected to an internal combustion engine in a plurality of compulsion systems is connected to each other by a controller area network (CAN) which is internationally standardized. When an abnormality occurs in an internal combustion engine in any of propulsion units, if an electronic control device connected to the abnormal internal combustion engine detects an abnormality, it makes a spark plug of its internal combustion engine fail based on the abnormal signal, and the abnormal signal is transmitted to an electronic control device connected to the other normal internal combustion engine to make a spark plug of a normal internal combustion engine fail, so that an engine speed of each internal combustion engine is reduced.